It was January 1983 and Toronto police had called her parents in the middle of the night to ask if she knew the whereabouts of her best friend and Grade 4 classmate, Sharin' Morningstar Keenan, who was missing.

"The sense of responsibility that immediately you take on as someone's friend: 'Well, why don't I know where she is?'" recalled the St. John's-based writer.

Keenan disappeared on Jan. 23, 1983, after playing in a Toronto park. Nine days later, her body was found in a refrigerator in a rooming house in the city.

The killer has never been found.

De Mariaffi's mother worked at their school, teaching a kindergarten class that included Keenan's younger brother.

De Mariaffi said the experience greatly affected her family and was the inspiration behind her new crime thriller novel, "The Devil You Know."

"It travels with me. I don't think it's ever really not there," said de Mariaffi, whose short-story collection "How to Get Along With Women" was longlisted for the 2013 Scotiabank Giller Prize.

"Part of my thinking on it — I guess when my daughter was little and then leading up to writing this novel — was this really important realization that I will never not be that girl. I will never not have had that experience.

"Sounds like an odd thing to say, but there's a great deal of acceptance that has to go along with that: 'Wow, this really happened.' Because we're so used to, I think, looking at these things as isolated events that they take on a storybook feeling, which is partially why the story is so interesting to me."

"The Devil You Know" follows 22-year-old budding Toronto journalist Evie Jones as she takes on a daunting assignment: staking out Paul Bernardo's home following his arrest in February 1993.

Already plagued by thoughts of the murder of her best friend Lianne 11 years prior, Evie is further spooked by suspicions that a man has been peeping on her from the fire escape at the back of her apartment building.

Like Evie, de Mariaffi said she also had a bit of journalism experience, having worked at the University of Guelph newspaper. She also had an apartment with a fire escape in downtown Toronto in the '90s.

The seed for the novel was planted when she started thinking back to that time and imagining a single woman living in a bachelor apartment, wondering if someone is stalking her or if it's just anxiety. She decided to weave that into her other story idea about the aftermath of a young girl's disappearance.

She set the story in 1993-era Toronto because it was "a time of great fear" in the city, "a time of a great villain," she said.

"I was a teenager through the late '80s and early '90s, so that time when the city was so coloured by fear of the Scarborough rapist, and then later on the girls who went missing down in Niagara," said de Mariaffi.

"That moment when we realized this was all the same villain was really I think monumental — not just for Ontario. I hear this from people across Canada. And then of course my own experience being Sharin' Keenan's friend in Grade 4 when she went missing."

While these events affected her childhood, De Mariaffi realized when her daughter was born that she "did not want to infuse her with all that fear."

She felt it was important to teach her "how to move in the world independently," which included letting her take the streetcar to school when they lived in Toronto.

"I recognized that this would be a real possibility — it was going to be really possible that I would get to the point where she was going off to nursery school, or school, or day care, or whatever and feel a lot of anxiety and I didn't want to do that," De Mariaffi said.

"I wanted to have a girl who felt powerful in the world, so I feel like I did a lot of the thinking on it back then, which maybe allowed me to approach the novel now."